[Excessive 7-14-sec positive spikes during REM sleep in monozygotic non-epileptic twins with speech retardation...

6-14/sec positive spikes (PS) (in our cases 7-14) were observed during 6 all-night sleep, recordings in one pair of monozygotic twins (aged 7 years), who had severe speech retardation, no epilepsy and were otherwise normal (CAT were normal). The EEG during wakefulness and sleep showed multifocal independent spikes over the left mid-temporal and right parieto-occipital area. The 7-14 PS, which were similar in both twins, occurred slightly during light sleep, were absent during slow sleep and were most prominent during REM sleep (mean=6.3 sec of PS bursts/min of REM). During REM sleep, the 7-14 PS bursts were negatively related to bursts of eye movements; PS were 7 times more frequent in the intervals between than during bursts of eye movements. In addition, long bursts of PS (up to 6 sec) might interupt the bursts of eye movements suggesting a functional antagonism between mechanisms (still unclear) responsible for PS and for REM. The predominance of PS during REM sleep and the inverse relationship with eye movements are not peculiar to our case, since similar findings have been reported in other cases (TSUZUKI 1967; OKUMA et al. 1968). During the sleep stages when Ps occurred spontaneously, PS could also be evoked by a click or a tone, with a latency of 1, 5-2 sec.